Co doped V₃O₇·H₂O nanobelt cathode with a three-stage ion intercalation mechanism for enhancing the electrochemical kinetics of aqueous zinc-ion batteries

Vanadium-based cathode materials have garnered considerable attention due to their high theoretical capacity (over 300 mA h g−1), flexible electrochemical ion insertion properties, and elevated valence states. However, their low electrical conductivity and tendency to dissolve in electrolytes have impeded progress in developing grid-scale energy storage systems. To overcome these challenges, Co2+-doped V₃O₇·H₂O (Co: V₃O₇·H₂O) cathode materials were prepared using a one-step hydrothermal method to address the issues mentioned above. The synthesized Co: V₃O₇·H₂O material provided sufficient pathways for fast ion diffusion, delivering a high reversible capacity of 354.2 mAh g−1 at 0.1 A g−1, outstanding cycling stability over 1000 cycles at the same current density with a Coulombic efficiency exceeding 99%, and a reasonable energy density of 460.46 Wh kg−1. To gain deeper insight into the storage mechanism of Co: V₃O₇·H₂O, various characterization techniques were employed, including ex situ X-ray photoelectron spectroscopy (XPS), which clarified the intercalation behavior of the cathode material. These results provide important guidance for the development of stable vanadium-based cathodes for next-generation aqueous zinc-ion batteries (AZIBs).